The invention relates to cleaning compositions, methods for manufacturing a cleaning composition, and methods for using a cleaning composition to clean and brighten an aluminum surface.
Many vehicle washing compositions include hydrofluoric acid as a cleaning and polishing agent. Hydrofluoric acid works well for cleaning and polishing aluminum. Cleaning compositions containing hydrofluoric acid are used in commercial automobile and/or truck washing facilities. The presence of hydrofluoric acid in a cleaning composition presents a health hazard.
A composition for use on aluminum, which includes hydrofluoric acid, is described by U.S. Pat. No. 3,988,254 to Mori. Cleaning compositions for use on aluminum which have been developed as replacements for compositions containing hydrofluoric acid are described by U.S. Patent Nos. 5,248,399 to Meguro, et al.; U.S. Pat. No. 5,336,425 to Aoki, et al.; U.S. Pat. No. 5,382,295 to Aoki, et al.; U.S. Pat. No. 5,464,484 to Rodzewich; and U.S. Pat. No. 5,514,293 to Shimakura, et al.
A cleaning composition is provided according to the invention. The cleaning composition includes a product of mixing an acid component having a first pka of about 2.5 or less and being less oxidizing than nitric acid, a source of phosphoric acid component to provide phosphoric acid, and an oxidant component. The molar ratio of oxidant component to phosphoric acid component is preferably between about 2:1 and about 1:2, and the molar ratio of oxidant component to acid component is preferably between about 1:3 and about 1:5.
A method of cleaning an aluminum surface is provided. The method includes a step of applying the cleaning composition to an aluminum surface, and rinsing the cleaning composition from the aluminum surface.
A method for manufacturing a cleaning composition is provided. The method includes a step of mixing an acid component having a first pKa of about 2.5 or less and being less oxidizing than nitric acid, a source of phosphoric acid component to provide phosphoric acid, and an oxidant component.
The cleaning composition according to the invention can be used to clean and brighten aluminum surfaces. The cleaning composition is particularly useful for cleaning aluminum surfaces provided on the exterior of motor vehicles such as automobiles, pick-up trucks, trucks, and trailers. Because of its effectiveness in brightening aluminum surfaces, the cleaning composition according to the invention can be referred to as a brightening composition.
The cleaning composition can be made available as a concentrate or as a use solution. The concentrate can be made available as a composition containing or not containing water. The use solution is preferably obtained from the concentrate by adding water to the concentrate. In general, it is expected that the cleaning composition will be transported as a concentrate and then diluted at the use location to provide a use solution. Preferably, the use solution will contain between about 0.1 wt. % and about 20 wt. % cleaning components, and more preferably between about 1 wt. % and about 5 wt. % of cleaning components. It should be understand that the term xe2x80x9ccleaning componentsxe2x80x9d refers to the non-water portion of the cleaning composition that is responsible for providing the cleaning and brightening properties.
The cleaning composition comprises a product of mixing an acid component having a first pka of about 2.5 or less and being less oxidizing than nitric acid, a source of phosphoric acid component, and an oxidant component. The cleaning composition preferably includes a molar ratio of oxidant component to phosphoric acid of between about 2:1 and about 1:2, and a molar ratio of oxidant component or phosphoric acid to acid component of between about 1:3 and about 1:5. Preferably, the molar ratio of oxidant component to phosphoric acid is about 1:1.
The acid component having a first pka of about 2.5 or less and being less oxidizing than nitric acid that can be used according to the invention includes acids that are generally considered strong and non-oxidizing acids. The acid component, if it is oxidizing at all, is less oxidizing than nitric acid. Preferably, the acid component excludes nitric acid. The level of oxidization exhibited by an acid is reported in Lang""s Handbook of Chemistry, 13th Ed., McGraw-Hill Book Company. Exemplary acids that can be used according to the invention include sulfuric acid, phosphoric acid, polyphosphoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, imidiphosphoric acid, thiocyanic acid, and mixtures thereof The acid component can include a mixture of two or more acids having a first pka of about 2.5 or less and being less oxidizing than nitric acid.
The source of phosphoric acid component that can be used according to the invention includes any component that generates phosphoric acid when added to water. Exemplary sources of phosphoric acid include phosphoric acid, polyphosphoric acid, and oxides of phosphorus. Exemplary oxides of phosphorus include phosphorus tetraoxide, phosphorus hexaoxide, and phosphorus decaoxide. A preferred source of phosphoric acid is phosphoric acid. The source of phosphoric acid component can include a mixture of two or more sources of phosphoric acid.
The oxidant component that can be used according to the invention includes those oxidants which exhibit an oxidation-reduction potential of greater than 0 volts, preferably greater than 0.5 volts, and even more preferably greater than 1.00 volts when measured as half-reactions at 25xc2x0 C. as reported in Lange""s Handbook of Chemistry, 13th ed., McGraw-Hill Book Company. Exemplary oxidants that can be used according to the invention include peroxygen compounds, ozone, halogens and their oxides, manganese compounds, chromium compounds, cerium compounds, vanadium compounds, copper compounds, silver compounds, iron compounds, titanium compounds, and mixtures thereof. Examples of peroxygen compounds include hydrogen peroxide, physical adducts of hydrogen peroxide, peroxycarboxylic acids and their salts and esters, peroxysulfuric acids and their salts and esters, peroxyphosphoric acids and their salts and esters, perborates, pertungstic acid, and permanganates. Examples of physical adducts of hydrogen peroxide include sodium percarbonate and urea peroxide. Examples of peroxycarboxylic acids include performic, peracetic, peroctanoic, 2-ethylhexanoic, and ocatdecanoic. Examples of peroxysulfuric acids include monoperoxysulfuric acid, diperoxysulfuric acid, dodecylbenzenepersulfonic acid, and octylpersulfonic acid. Examples of perborates include alkali metal salts such as sodium or lithium perborate and also perboric acid. Examples of permanganates include alkali metal salts such as sodium or potassium permanganate and also permanganic acid. An exemplary manganese compound includes manganese dioxide. Exemplary halogen compounds include chlorine, bromine, iodine, and their interhalogen compounds; chlorate, bromate, and iodate salts; chorine dioxide and bromine dioxide; chloric, bromic, and iodic acids and their salts; perchloric, perbromic, and periodic acids and their salts; quaternary ammonium/phosphonium/sulfonium polyhalides such as choline diiodochloride, tetramethylammonium tribromide, hexadecyltrimethylphosphonium dibromochloride, and octyltrimethylsulfonium dichlorobromide; inorganic polyhalides such as potassium tribromide, sodium dibromochloride, and lithium dichloroiodide. Exemplary chromium compounds include chromic acid and its alkali and metal salts. Exemplary cerium compounds include cerium (IV) salts such as CeO2 or Ce(OH)4. Exemplary vanadium compounds include vanadium (III or higher) salts such as VCl3 and V2O5. Exemplary silver compounds include silver (I) systems such as AgO. Exemplary iron compounds include iron (III) salts such as Fe2O3 or FeCl3. Exemplary titanium compounds include titanium (IV) salts such as TiO2 or TiI4. Hydrogen peroxide is a preferred oxidant according to the invention. The oxidant component can include a mixture of oxidants which provide a summation oxidation-reduction potential greater than 0 volts, more preferably greater than 0.5 volts, and more even more preferably greater than 1.00 volts.
The cleaning composition can be referred to as a xe2x80x9cproduct of mixingxe2x80x9d because it is believed that the components of the cleaning composition react. It is believed that it is desirable for the oxidant component to react with the phosphoric acid component, and for the acid component to promote the reaction between the oxidant component and the phosphoric acid component. Furthermore, it is believed that a reaction between the acid component and the oxidant component may occur. Preferably, the reaction between the acid component and the oxidant component, if it occurs at all, is disfavored relative to the reaction between the oxidant component and the phosphoric acid component. Because it is not necessarily clear what exact chemical components are present in the cleaning composition, it is believed appropriate to refer to the composition as a product of mixing.
The cleaning composition is preferably used at a temperature that is less than about 80xc2x0 C., and more preferably less than about 50xc2x0 C. It is expected the cleaning composition will be used at about ambient temperature.
The cleaning composition provides a use solution that is generally considered non-alkaline. Alkaline cleaners having a pH greater than 7 or 8 have a tendency to remove aluminum. Preferably, the use solution according to the invention has a pH of less than 7, more preferably less than 5, and even more preferably less than 3.
Aluminum surfaces are generally considered to be very hydrophobic. Furthermore, dirty aluminum surfaces are generally believed to be even more hydrophobic. The mixture of acid component, source of phosphoric acid component, and oxidant component are generally considered to exhibit hydrophilic properties. In order for the cleaning composition to clean and brighten the aluminum surface, it is desirable to have the cleaning composition penetrate to the aluminum surface to provide cleaning and brightening of the aluminum surface. The hydrophobicity of the aluminum surface discourages penetration of the cleaning composition to the aluminum surface. Accordingly, it is desirable for the cleaning composition to include a penetrant to help the cleaning composition wet the aluminum surface and thereby effect cleaning and brightening of the aluminum surface.
Preferred penetrants that can be used according to the invention include relatively hydrophobic surfactants. In general, it is believed that hydrophobic surfactants are desirable because they allow the brightening agent to penetrate to the aluminum surface. In general, the following classes of surfactants are preferred in the following order: cationic surfactants, amphoteric surfactants and anionic surfactants, and nonionic surfactants.
Cationic surfactants that can be used according to the invention as penetrants include those surfactants having the formula: 
wherein each of R1, R2, R3, and R4 include, individually or in combination, substituents including 6 to 24 carbon atoms, preferably 14 to 24 carbon atoms, and more preferably, 16 to 24 carbon atoms. Each of R1 to R4 can be linear, cyclic, branched, saturated, or unsaturated, and can include heteroatoms such as oxygen, phosphorous, sulfur, or nitrogen. Any two of R1 to R4 can form a cyclic group. Any one of three of R1 to R4 can be hydrogen. X is preferably a counter ion and preferably a non-fluoride counter ion. Exemplary counter ions include chloride, bromide, methosulfate, ethosulfate, sulfate, and phosphate. Preferred cationic surfactants include quaternary ammonium salts such as trialkylbenzyl quaternary ammonium salt, tetraalkyl quaternary ammonium salt, and pyridinium quaternary ammonium salt. A preferred cationic surfactant includes tetradecyl dimethylbenzyl ammonium chloride.
A preferred type of cationic surfactant includes imidazolines and more preferably alkyl imidazoline quaternary ammonium salts, wherein the alkyl group contains 6 to 24 carbon atoms and may be saturated and/or unsaturated. Preferred imidazolines include steryl imidazolines, isosteryl imidazolines, and mixtures of steryl imidazolines and isosteryl imidazolines. In general, steryl groups can be characterized as alkyl groups containing 16 to 18 carbon atoms that may be saturated and/or unsaturated. This type of cationic surfactant is believed to be available under the name Monastat from Unichemi.
Another preferred type of cationic surfactant includes alkyl ethoxylated and/or propoxylated quaternary ammonium salts (or amines). Preferably, the alkyl group contains between about 6 and about 24 carbon atoms and can be saturated and/or unsaturated. The degree of ethoxylation is preferably between about 0 and about 30, and the degree of propoxylation is preferably between about 0 and about 30, with the proviso that at least one of the degree of ethoxylation or the degree of propoxylation is at least one. Preferred alkyl ethoxylated quaternary ammonium salts include a degree of ethoxylation of between about 5 and 15. Preferred alkyl propoxylated quaternary ammonium salts include a degree of propoxylation of between about 5 and about 15. A preferred cationic surfactant is commercially available under the name Variquat K1215 from Goldschmidt. The applicants discovered that this cationic surfactant is particularly useful for providing the detergent composition with enhanced water hardness tolerance. Another preferred cationic surfactant is available under the name Varonic K205 from Goldschmidt. The applicants discovered that this cationic surface allows the detergent composition to exhibit enhanced degreasing and enhanced foam quality, and helps enhance water hardness tolerance.
The applicants discovered that water hardness may decrease the ability of the detergent composition to penetrate the soil present on an aluminum surface in order to clean and brighten the aluminum surface. It should be understood that hard water can be characterized as water containing greater than 100 ppm calculated as calcium carbonate. It should be understood that xe2x80x9c100 ppm calculated as calcium carbonatexe2x80x9d refers to the components within the water that contribute to the hardness although all the components are likely not calcium carbonate. The applicants discovered that certain surfactants can provide the cleaning composition with enhanced water hardness tolerance. Particularly preferred surfactants that enhance the water hardness tolerance of the cleaning composition include the alkyl ethoxylated and/or propoxylated quaternary ammonium salts, and, in particular, the surfactants available under the names Variquat 1215 and Varonic K205 from Goldschmidt.
The cleaning composition preferably includes a mixture of alkyl imidazoline quaternary ammonium salts, and alkyl ethoxylated and/or propoxylated quaternary ammonium salts. Preferably, the mixture is a mixture of Monastat surfactant, Variquat 1215 surfactant, and Varonic K205 surfactant. The weight ratio of each surfactant can be provided as between about 0.1 and about 10 relative to the other surfactant. Preferably, the weight ratio of each of the three surfactants is 1:1.
Amphoteric surfactants that can be used according to the invention as penetrants include those surfactants having the formula: 
wherein R1, R2, and R3 include, individually, or in combination, substituents including 6 to 24 carbon atoms, preferably 14 to 24 carbon atoms, and more preferably 16 to 24 carbon atoms. Each of R1 to R3 can be linear, cyclic, branched, saturated, or unsaturated, and can include heteroatoms such as oxygen, phosphorous, sulfur, or nitrogen. Any two of R1 to R3 can form a cyclic group. Y is preferably an anionic substituent such as carboxy, phosphorus derivative, sulfate, and sulfonate. Exemplary phosphorus derivatives include phosphate and phosphorus esters. The number of repeating units n can be about 1 to about 20, and preferably 1 to 10, and more preferably 1-3 and most preferably 1. Preferred amphoteric surfactants that can be used according to the invention include betaines, sultaines, imidazoline derivatives, and amine oxides. Preferred amphoteric surfactants include lauramine oxide, cocoamidopropyl betaine, and lauryl amphoacetate.
Anionic surfactants that can be used according to the invention as penetrants include those surfactants having the formula:
Rxe2x80x94Y
wherein R can be a saturated or unsaturated alkyl or aryl or aralkyl substituent including 6 to 24 carbon atoms, preferably 14 to 24 carbon atoms, and more preferably 16 to 24 carbon atoms. The substituent R can be linear, cyclic, branched, saturated, or unsaturated. Y is an anionic substituent that is preferably sulfonate, sulfate, phosphate, carbonate. Exemplary anionic surfactants include tetradecylether sulfate and dodecylbenzene sulfonate.
Nonionic surfactants that can be used according to the invention as penetrants include those surfactants having the formula: 
wherein R is a substituent having 1 to 24 carbon atoms, preferably 12 to 20 carbon atoms, and more preferably 15 to 20 carbon atoms. R can be linear, cyclic, branched, saturated, or unsaturated, and can include heteroatoms such as oxygen, phosphorous, sulfur, or nitrogen. R1 is H or CH3, and n is preferably between 1 and 30. Exemplary nonionic surfactants include alcohol ethoxylates, alkylphenol ethoxylates, EO/PO copolymers, and alkanolamides. Preferred nonionic surfactants include nonylphenol ethoxylate and myristeth-7.
The penetrant is preferably provided in an amount sufficient to help the cleaning composition penetrate soil that may be present on the aluminum surface so that the cleaning composition can reach the aluminum surface and clean and brighten the aluminum surface. The penetrant is preferably provided in an amount that provides a use solution containing between about 0.01 wt. % and about 20 wt. % penetrant, more preferably between about 0.1 wt. % and about 10 wt. % penetrant, and, even more preferably, between about 0.5 wt. % and about 5 wt. % penetrant. It should be appreciated that the penetrant is an optional component, and the cleaning composition can be provided without any penetrant.
It is believed that the acid component helps drive a reaction between phosphoric acid and the oxidant component. In one embodiment of the invention, the cleaning composition can be provided as a result of mixing the source of phosphoric acid component, the acid component, the oxidant component, and the penetrant. In an alternative embodiment of the invention, the cleaning composition can be provided as a multi-part system such as a two-part system. In a two-part system, the acid component can be combined with a mixture of the source of phosphoric acid component, the oxidant component, and the penetrant to provide a cleaning composition. The acid component can be provided as a liquid and the cleaning composition can be used as a spray, gel, or foam. In addition, the acid component can be introduced as a solid that dissolves. For example, the acid component can be provided in the form of polymeric beads or resins wherein the acid is covalently bonded to the resin. An exemplary solid acid includes sulfamic acid. It is believed that the cleaning composition would then dissolve the solid acid. In addition, the acid provided on beads can dissolve or it may not dissolve.
The cleaning composition according to the invention is preferably substantially free of hydrofluoric acid. This generally means that the cleaning composition is completely free of hydrofluoric acid, or if hydrofluoric acid is present, it is present in an amount where it presents no substantial health hazard. It is desirable that the presence of hydrofluoric acid need not be declared on packaging for the cleaning composition. It should be understood that the phrase xe2x80x9csubstantially free of hydrofluoric acidxe2x80x9d does not exclude the presence of fluoride anions and/or hydrofluoric acid present as a result of the water being used. It is pointed out that many municipalities fluorinate water, and that at certain pH levels there is an equilibrium relationship between hydrofluoric acid and fluoride anion.
When the cleaning composition is a product of mixing phosphoric acid, hydrogen peroxide, and sulfuric acid, a preferred composition can be described by the equation below where the weight fractions of the components are present in such ratios that the brightening effectiveness is xe2x89xa71.5 on a scale where 0=no brightening, 1=less brightening than commercial HF containing cleaning composition, 2=matches commercial HF containing cleaning composition brightening, 3=better than commercial HF containing cleaning composition brightening, H=wt. % of hydrogen peroxide [35% active basis] in decimal form, S=wt. % of sulfuric acid in decimal form, and P=wt. % of phosphoric acid [75% basis] in decimal form.
1.5xe2x89xa6[1.9*H+0.64*S+5.25*H*Sxe2x88x921.17*H*P+2.34*S*Pxe2x88x923.84*H*S*Pxe2x88x924.04*H*S(Hxe2x88x92S)+6.85*H*P(Hxe2x88x92P)+11.18*S*P (Sxe2x88x92P)]
A preferred composition corresponding to the above equation is provided by about 1 mole hydrogen peroxide/1 mole phosphoric acid/at least 5 moles sulfuric acid.
The cleaning composition can be provided in the form of a solution, emulsion, microemulsion, suspension, solid, pellets, powder, gel, and foam. The cleaning composition can include an aqueous or nonaqueous solvent. A preferred aqueous solvent is water, which may be added directly to the composition at the manufacturing stage or the composition may be added/injected into a water stream at the point of use to provide a use solution. Water insoluble oils such as mineral oil or spirits, paraffins, methyl soyate, etc., can be optionally added to modify wetting and drying properties. Water insoluble oils are generally considered to be oils that are less than 1 wt. % soluble in water.
The appearance of the cleaning composition can be modified by the addition of thickeners, dyes, fragrances, and other conventional additives used for cleaners. In addition, the cleaning composition can include builders to soften water, anti-redeposition agents, and antimicrobial actives.
The cleaning composition can be prepared by mixing the acid component, the source of phosphoric acid component, and the oxidant component. The components can be mixed together in the presence or absence of any of the additional components identified above. It is generally desirable to provide the cleaning composition at about room temperature. The reaction between the oxidant component and the phosphoric acid component is generally exothermic. Accordingly, the cleaning composition will tend to increase in temperature as the oxidant component and the phosphoric acid component react.
The composition according to the invention can be used as a two component mixture of acidic component (part A) and oxidant component (part B). The acidic component preferably includes a mixture of the phosphoric acid component and the acid component. The two components can be combined prior to use of the cleaning composition. The penetrant can be provided as part of either the acidic components (part A) or the oxidant component (part B) or as a separate component (part C). Although the cleaning composition is preferably prepared from a two-part system, the cleaning composition can be provided as a one-part system.
The cleaning composition according to the invention can be provided as a cleaning composition that is generated in situ. For example, chlorine dioxide can be generated by a variety of routes including hypochlorite/chlorite mixtures, halogen/chlorite mixtures, polyhalide/chlorite mixtures, and acid/chlorite mixtures. Polyhalides such as those described in U.S. patent application Ser. Nos. 09/277,592 and 09/277,626 can be generated via reaction between an oxidant, a halide source, and a material selected from inorganic halide or quaternary ammonium/phosphonium/sulfonium salts. Peroxyphosphoric acids can be obtained by oxidation of phosphoric or polyphosphoric acid in the presence of a strong acid. Peroxysulfuric acids can also be prepared by reaction of an oxidant with sulfuric acid. The entire disclosures of U.S. patent application Ser. Nos. 09/277,592 and 09/277,626 are incorporated herein by reference.
A method of brightening aluminum with the cleaning composition includes a step of treating either a precleaned or soiled aluminum surface with the cleaning composition, waiting a sufficient period of time for the brightening to occur, and then removing the cleaning composition from the surface. The cleaning composition can be applied to the aluminum surface by spraying or the aluminum can be dipped or soaked in a cleaning solution reservoir. The cleaning solution reservoir can be mechanically agitated. The spray can be as the concentrate or diluted into an aqueous or nonaqueous medium. The nonaqueous medium can be either a liquid with a boiling point above ambient temperature or as a liquefied gas. Examples of liquefied gas include carbon dioxide, air, oxygen, helium, and nitrogen.
The aluminum surface could be part of a motorized vehicle such as a car, truck, boat, ship, plane, jet, helicopter, or train. It could also be part of a fabricated article such as piping, storage tanks, cookware, medical device or a can. It could also be part of an architectural structure such as window parts, door parts, window/door screens, and blinds. Additionally, it could also be part of an electronic device such as a circuit board, computer chip, heat sink, light ballast, or even wiring itself.